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Application Notes

Circuits from the Lab

New Product Briefs

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Power Management Home

Application Notes

AN-1253: Layout Considerations for Digital Power Management (ADP1046A)

The ADP1046A secondary side digital power controller features analog-to-digital converters, integrated I2C communication, analog comparators, and digital compensation. Layout is crucial for complex mixed signal devices with closely spaced input and output functions, so proper care must be taken to avoid hazards. This 7-page Application Note provides guidelines to avoid noise coupling and techniques for proper grounding.

AN-1213: Powering the AD9788 800 MSPS TxDAC Digital-to-Analog Converter Using the ADP2105 Synchronous Step-Down DC-to-DC Regulator for Increased Efficiency

This 3-page Application Note describes a circuit that uses a pair of ADP2105 synchronous step-down dc-to-dc regulators to provide the individual power supply rails required for the AD9788 dual channel, 16-bit, high dynamic range TxDAC® digital-to-analog converter at greater than 85% efficiency.

AN-1211: Powering the AD9268 Dual Channel 16-Bit, 125 MSPS Analog-to-Digital Converter with the ADP2114 Synchronous Step-Down DC-to-DC Regulator for Increased Efficiency

This 3-page Application Note describes a circuit that uses the ADP2114 dual channel synchronous step-down dc-to-dc regulator to provide the individual power supply rails required for the AD9268 dual 16-bit, 125 MSPS, 1.8 V ADC at 85% efficiency.

AN-1210: Powering the AD9272 Octal Ultrasound ADC/LNA/VGA/AAF with the ADP5020 Switching Regulator PMU for Increased Efficiency

This 4-page Application Note describes a circuit that uses the ADP5020 power management unit to provide the individual power supply rails required for the AD9272 octal LNA/VGA/AAF/ADC and crosspoint switch.

Circuits from the Lab

CN0280: Robust Completely Isolated Current Sense Circuit with Isolated Power Supply for Solar Photovoltaic Converters

This completely isolated current sensor with isolated power source is highly robust and can be mounted close to the sense resistor for accurate measurements and minimum noise pickup. The 16-MHz output data stream from a sigma-delta modulator is processed by a DSP using a SINC3 digital filter. Ideal for monitoring the ac current in solar photovoltaic (PV) converters, the circuit can handle peak ac voltages of several hundred volts and currents between a few mA and 25 A.

Fully Isolated Lithium Ion Battery Monitoring and Protection System (CN0235)

Lithium ion (Li-Ion) battery stacks contain a large number of individual cells that must be monitored correctly in order to enhance the battery efficiency, prolong the battery life, and ensure safety. The 6-channel AD7280A devices in this circuit act as the primary monitor, providing accurate voltage measurement data to the System Demonstration Platform (SDP-B) evaluation board; the 6-channel AD8280 devices act as the secondary monitor and protection system. Both devices can operate from a single wide supply range of 8 V to 30 V and operate over the industrial temperature range of −40°C to +105°C. The AD7280A contains an internal ±3-ppm reference that allows a cell voltage measurement accuracy of ±1.6 mV. The ADC resolution is 12 bits and allows conversion of up to 48 cells within 7 μs. The AD8280 functions independently of the primary monitor and provides alarm functions, indicating out of tolerance conditions. It contains its own reference and LDO, both of which are powered from the battery cell stack. The reference, in conjunction with external resistor dividers, is used to establish overvoltage/undervoltage trip points. Each channel contains programmable deglitching circuitry to avoid alarming from transient input levels. The AD7280A and AD8280, which reside on the high voltage side of the battery management system, have a daisy-chain interface, allowing up to eight AD7280A’s and eight AD8280’s to be stacked together and 48 Li-Ion cell voltages to be monitored. Adjacent AD7280As and AD8280s can communicate directly, passing data up and down the stack without the need for isolation. The master devices on the bottom of the stack use the SPI interface and GPIOs to communicate with the SDP-B evaluation board. High-voltage galvanic isolation is required to protect the low-voltage side of the SDP-B board at this interface. The ADuM1400 and ADuM1401 digital isolators and the ADuM5404 digital isolator with integrated dc-to-dc converter combine to provide the required eleven channels of isolation in a compact, cost effective solution. The ADuM5404 also provides isolated 5 V to the VDRIVE input of the lower AD7280A and the VDD2 supply voltage for the ADuM1400 and ADuM1401 isolators.

New Product Briefs

April 2014

Digital Controller for isolated dc-to-dc power supplies matches analog performance

adp1055The ADP1055 digital controller combines high-resolution, high-speed ADC sensing with proprietary nonlinear transfer functionality to achieve wide bandwidth and transient response equivalent to traditional analog controllers. The extremely versatile digital controller has six PWM (pulse-width modulation) logic outputs that can be programmed via the PMBus interface using an easy-to-use graphical user interface (GUI). The device enables high-efficiency topologies including full bridge—with precision drive timing and control of secondary synchronous rectifiers. GPIO can be configured for active clamp secondary energy efficient snubbing. Energy efficiency is further optimized using adaptive dead-time compensation, programmable light load mode, and low device power consumption. Accurate analog and digital fault signaling is provided via the PMBus and configurable GPIO. The device also records first instance of fault and provides ‘Black Box’ fault history recording capability—ideal for analyzing system failure mechanisms. The robust design provides protection against overcurrent (OCP), overvoltage (OVP), undervoltage (UVLO), and overtemperature (OTP). Operating on a single 3.0-V to 3.6-V supply, the ADP1055 draws 63 mA in normal mode and 100 µA in shutdown mode. Available in a 32-lead LFCSP package, it is specified from –40°C to +125°C and priced at $4.60 in 1000s.

March 2014

Precision Analog Front End and Controller for testing and monitoring battery cells

ad8450The AD8450 precision analog front end for testing and monitoring battery cells includes a precision programmable gain instrumentation amplifier (PGIA) that measures the battery’s charge/discharge current and a programmable gain difference amplifier (PGDA) that measures the battery’s voltage. Internal laser trimmed resistor networks set the PGIA gain to 26×, 66×, 133×, or 200× and PGDA gain to 0.2×, 0.27×,0.4×, or 0.8×, optimizing performance over the rated temperature range. The device simplifies designs by providing high accuracy, low drift over temperature, flexibility, and high reliability in a space-saving package. Voltages at ISET and VSET inputs set the constant voltage and constant current values. Switching between these modes is automatic and transparent to the system. The MODE input selects between charge and discharge modes; and the VCTRL output interfaces directly with PWM controllers, such as the ADP1972 and ADP1974. Current sharing balances charge among multiple batteries. Protection features include overvoltage and overcurrent detection. Operating on ±15-V and +5‑V supplies, the AD8450 dissipates 200 mW. Available in an 80-lead, 14-mm ×14-mm × 1‑mm LQFP package, it is specified from –40°C to +85°C and priced at $6.95 in 1000s.

Digital Controller for isolated power supply with PMBus interface

adp1050The ADP1050 advanced digital controller with PMBus™ interface facilitates high-density, high-efficiency dc-to-dc power conversion. The ADP1050 has four programmable pulse-width modulation (PWM) outputs and is capable of controlling most high efficiency power topologies with synchronous rectification. Voltage-mode control with high-speed, input line feed-forward provides enhanced input transient response. Adaptive dead-time compensation improves efficiency and programmable light-load operation reduces power losses. The flexible state machine is programmed using an intuitive GUI, reducing design time. Operating on a 3.0-V to 3.6-V supply, the ADP1050 draws 28.5 mA in normal mode and 50 µA in shutdown mode. Available in a 20-lead LFCSP package, it is specified from –40°C to +125°C and priced at $3.40 in 1000s.

PWM Controller for battery test applications operates in buck or boost modes

adp1972The ADP1972 constant-frequency, voltage-mode, pulse-width modulation (PWM) controller for asynchronous buck- or boost-mode dc-to-dc converters is designed for use in high efficiency battery testing applications partnering with the AD8450. The ADP1972 operates as a buck converter in battery charge mode and a boost converter in recycle mode to return energy to the input bus. The high-voltage supply pin can withstand 60 V max, reducing the need for additional system supply voltages. The flexible device features precision enable, selectable buck or boost mode, internal and external synchronization with programmable phase shift, programmable duty cycle, and programmable peak hiccup current limit. Protection features include soft start to limit inrush current during startup, undervoltage lockout, and thermal shutdown. The COMP pin provides external control of the PWM operation and the FAULT pin can be signaled to disable the DH and DL outputs in case of an external fault condition. Operating on a 6.0-V to 60-V supply, the ADP1972 draws 1.5 mA in normal mode and 15 µA in shutdown mode. Available in a 16-lead TSSOP package, it is specified from –40°C to +125°C and priced at $3.50 in 1000s.

Integrated Power Solutions include four buck regulators, voltage monitor, watchdog, and reset

adp5053The ADP5051 and ADP5053 integrated power solutions combine four high-performance buck regulators and a supervisory circuit with voltage monitor, watchdog, and manual reset in a single small package that meets demanding performance and board space requirements. The devices enable direct connection to input voltages up to 15 V. Two channels integrate high-side power MOSFETs and low-side MOSFET drivers. External NFETs can be used in low-side power devices to achieve an efficiency optimized solution and deliver a programmable output current of 1.2 A, 2.5 A, or 4 A. These channels can be connected in a parallel configuration to provide a single output with up to 8 A of current. The other two channels integrate both high-side and low-side MOSFETs to deliver output current of 1.2 A. The switching frequency can be programmed externally or synchronized to an external clock. A precision enable input on each channel simplifies power-up sequencing or adjustable UVLO thresholds. Supervisory circuits include a voltage monitor, watchdog timer, and manual reset function. The ADP5051 adds an optional I2C interface that provides flexible configuration options, including adjustable and fixed output voltages, junction temperature overheat warning, low input voltage detection, and dynamic voltage scaling. Operating on a single 4.5‑V to 15-V supply, the ADP5051/53 draw 4.8 mA of quiescent current, which drops to 25 µA in shutdown mode. Available in 48-lead LFCSP packages, they are specified from –40°C to +125°C junction temperature and priced at $4.59/$3.79 in 1000s.

Technical Articles

Frederik Dostal, Digital power management without code qualification, Power Systems Design, 2014-03-03

Glenn Morita, Noise-Reduction Network for Adjustable-Output Low-Dropout Regulators, Analog Dialogue, 2014-03-03

Maurice O'Brien, Integrated Power Management Unit Simplifies FPGA-Based System, Electronics Maker, 2013-12-28

Maurice O'Brien, Highest Power Density, Multi-Rail Power Solution For Space-Constrained Applications, Analog Dialogue, 2013-11-01

Frederik Dostal, Power Management for Health Care Applications, Power Systems Design, 2013-10-17

Xing Xing, N.X. Sun, and Baoxing Chen, High-Bandwidth Low-Insertion Loss Solenoid Transformers Using FeCoB Multilayers, IEEE Transactions on Power Electronics, 2013-09-01

Maurice O'Brien, Integrated power management enables smaller machine vision systems, Power Systems Design, 2013-05-17

Jon Kraft, Convert a Buck Regulator into a Smart LED Driver, Including Dimming, Analog Dialogue, 2013-03-06

Jon Kraft, Convert a buck regulator into a high-current LED driver, Power Systems Design, 2013-01-26

Mark Cantrell, Optimizing power conversion for isolated sensor interfaces, EDN, 2012-12-04

Webinars and Tutorials

Galvanic Isolation for Power Supply Applications -- This seminar discusses isolation and isolation technologies in terms of signal transmission methods and isolation materials, including optocouplers and digital isolators. Ii covers isolation usage, including current sensing, gate driver, and communication functions in ac-to-dc, motor control, hybrid electrical vehicles, PV, and other power supply applications.

Solving Isolation Challenges in Power Conversion Applications - This webcast will present solutions to isolation challenges in power conversion applications. Among the topics to be discussed are the limitations of traditional methods of isolation (such as utilization of optocouplers and pulse transformers) vs. more efficient and cost effective solutions that utilize digital isolators. If you are currently using optocouplers and pulse transformers, this is a webcast you should attend.

Design Techniques for reducing power consumption and harmful thermal events in industrial designs - This webcast will present: typical analog module configuration and how to calculate the maximum ambient temperature that the system can tolerate, new technology to reduce the power dissipated in the module (regardless of what output load is connected), and the performance of these devices when the supply is run from a switching regulator rather than with a linear regulator.

Fundamentals of Designing with Semiconductors: Powering Your Circuit - What is important about a power supply and how does it work? What different types of power supplies and conversion methods are used? How can a power supply affect the signal chain and how do you select the best regulator for your circuit? This webcast will also explain noise, ripple, line and load regulation, power supply rejection ratio, the effects of temperature change, and other specifications that impact power supply performance.

 

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